Melt most of the chocolate in a bowl over hot water, leave enough chocolate to grate for a topping.
Pour the beans into a sieve with a bowl below to catch all the bean juice.
Whisk the bean juice with an electronic whisk for a few minutes while the chocolate melts.
Add the beans, and maple syrup to the melted chocolate and blend together in a jug blender or food processor. You may have to scrape down the sides several times.
Continue to whisk the bean juice (AKA aquafaba) until stiff peaks are formed, this takes about 8-10 mins in total with an electric whisk.
Stiff peaks are when you can turn the bowl upside down and the mixture doesn’t move. With aquafaba you don’t need to worry about over-whisking.
Fold the chocolate bean mixture into the aquafaba then pour it into 4 small glass dishes.
Chill for an hour then sprinkle the mousse with grated chocolate.
Keep the protein mousse in the fridge and enjoy within 3 days.